For example, there is known a waterproof structure of a linear motion mechanism described in PTL 1.
The waterproof structure of PTL 1 is configured to ensure sealability in such a way that an opening portion for water to enter is closed with two pieces of sealing members, a wedge portion provided on a slider is located between the two pieces of sealing members, and the wedge portion contacts with the two pieces of sealing members along with linear movement of the slider.